The examination of performance characteristics of a beta‐type Stirling engine with a rhombic mechanism: The influence of various working fluids and displacer piston materials

Abstract

In this study, to develop a power generation system that can use renewable energy resources more efficiently, a beta-type Stirling engine with rhombic mechanism was designed and manufactured. Kinematic and thermodynamic analyses of a beta-type Stirling engine were performed numerically in the Fortran program.Volume and pressure changes depending on crankshaft angle of Stirling engine were made using the isothermal analysis. The effects of the basic parameters related to engine performance, such as working fluid mass, charge pressure, heater, and coolant temperatures, on the net work amount were investigated. Five different gases, including helium, air, nitrogen, carbon dioxide, and argon, were used as a working fluid in experimental studies. The effects of all these gases on engine performance characteristics were examined at charge pressures of 1 to 5 bar for two different displacer pistons made of stainless steel and titanium material. The performance characteristics of Stirling engine manufactured were tested using a specially designed electrical heater, at 727 C hot end and 27 C cold end temperature, depending on engine speed. In all experimental studies, maximum power output was acquired to be 215.48 W, at 4 bar and 550 rpm when a stainless steel displacer piston and helium gas as a working fluid were used, and maximum torque value was acquired to be 7.54 Nm, at 5 bar and 150 rpm. The lowest engine power output among maximum engine powers was acquired to be 34.66 W when argon gas was used as a working fluid at 3 bar and 300 rpm, using a displacer piston made of titanium material. Maximum power output acquired in the experimental studies using a stainless steel displacer piston and helium; it was determined that it is 72.12%, 73.69%, 241.49%, and 288.81% higher than the engine power acquired by nitrogen, air, carbon dioxide, and argon gases, respectively.

The investigation of effects on the engine performance characteristics of different channel geometries in the displacer cylinder for a beta-type Stirling engine with the slider-crank drive mechanism

“…According to the values acquired in the tests carried out by O ¨zgo¨ren and C xetinkaya, 30 they determined that the power values of air and helium working fluids were similar to each other, and although the power values were different due to different engine types and sizes, the power values were higher in the tests with helium. In the study by Erol and C xalıs xkan, 46,47 it was indicated that the working fluid had significant impacts on engine performance characteristics. It was stated that reducing losses in the amount of heat transferred to the engine body and working fluid in the heater in Stirling engines would positively affect engine power.…”

The effects of different channel geometries in the displacer cylinder, working fluids, and engine speed on the energy and exergy performance characteristics of a β-type Stirling engine with a slider-crank drive mechanism

“…They computed the total exergy efficiency of the system as 64.26%. Erol and C xalıs xkan 33 and Erol et al 34 determined the impacts of two displacer pistons made of different materials on the engine performance characteristics of a b-type Stirling engine with a cylinder volume of 365 cm 3 using helium, nitrogen, air, carbon dioxide, and argon gases as working fluids by employing the thermodynamic analysis method. As a result, they demonstrated that the best engine performance conditions were acquired when a stainless steel displacer piston was used at a charge pressure of 4 bar and an engine speed of 550 rpm with helium as the working fluid.…”

A new second order thermal model for accurate simulation of the transient and steady–state response of beta-type Stirling engines based on time-varying calculation of thermal losses

“…42 The influence of working mediums and the material of the displacer piston to the performance was also investigated. 43,44 Rogdakis et al 45 introduced a numerical time-dependent model based on nodal analysis. The model took into account the convective heat transfer between the gas and the cylinder walls, the metal matrix temperature of the regenerator which varies spatially and temporally, the variation of the working medium pressure and the pressure drop due to friction losses as well as the pressure drop in the buffer space.…”